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Scope:

INTRODUCTION AND SUMMARY

System Development Corporation (SDC) has performed a study to
survey the characteristic use patterns of privately operated
automobiles in six major metropolitan areas: Los Angeles, Houston,
Cincinnati, Chicago, Minneapolis- St. Paul, and New York City. The
study was conducted under jointly sponsored research contracts to
the National Center of Air Pollution Control, Department of Health,
Education, and Welfare, and the Coordinating Research Council, Inc.
The purpose of the study was to obtain data necessary to develop
composite average driving patterns that would serve as a basis for
designing new teat cycles for vehicle emission control devices.

The findings of the surveys in each city have been published in
a series of SDC Technical Memorandum, TM-(L)-4119, Volumes 0
through 6. This report presents a summary of the data from all six
cities and some comparison between cities. Although strict
interpretation of the results of classical hypothesis testing would
seem to indicate that there are significant differences in the
automobile utilization and trip descriptions, an examination of the
individual and composite distributions of the various statistics
indicates that there are many similarities. The results for each
city showed that there were six different typical daily driving
patterns which stood out clearly. The distribution of these daily
patterns was quite similar among Houston, Cincinnati, Chicago, and
Minneapolis-St. Paul, while New York differed in having more zero
trip-days and Los Angeles had more multiple trip-days. Section Two
presents the n-trip pattern days for each city and a discussion of
their similarities and differences.

Automobile utilization, as characterized by trip start times,
trip purposes, weekday-weekend division of trips, and types of
routes traveled, demonstrates statistical similarities among all
cities on weekends. While the statistical tests rejected hypotheses
of homogeneity in most cases for weekday utilization, the number of
daily trips, the route types, and the weekday-weekend distributions
were somewhat similar for the four cities other than New York and
Los Angeles. Section Three presents the distributions of the
automobile utilization variables and an interpretation of their
comparisons.

The trip descriptors compared were trip distance, trip elapsed
time, stops with engine running, average speed, elapsed time
between trips, indoor-outdoor parking between trips and overnight,
and overnight fuel tank readings. While New York was different from
the other cities in almost all respects, and the stops with engine
running exhibited no similarities, the other cities were quite
homogeneous in all except weekday elapsed time and average speed.
These distributions are discussed in Section Four.

Tables S-1 and S-2 summarize the data gathered in each of the
six cities for weekday and weekend automobile utilization. The data
base for the survey includes 21,501 weekday trips and 7,842 weekend
trips made in 946 private automobiles. In addition, we analyzed 809
weekday trips and 261 weekend trips made by about 20 taxicabs in
the city of New York. A trip was defined as the period from
engine-on to engine-off with the engine remaining off for more than
five minutes. Tables S-3 and S-4 summarize the statistical
variables that describe the average weekday and weekend trip in
each of the six cities. In order to segregate data describing
driving behavior on surface streets and on freeways, trips that
involved freeway driving were divided into trip segments. Each
segment included the part of the trip that was made on one type of
road or the other. Generally, freeway trips contained three or more
segments. Tables S-5 and S-6 summarize the data on segments of
weekday and weekend trips for each of the six cities.

It should be noted that all of the tests used to compare the
distributions are based on classical statistical techniques.